Neurosurgery notes/Tumours/Sellar tumours/Craniopharyngioma/Types of craniopharyngioma/Papillary craniopharyngiomas

Papillary craniopharyngiomas

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Types of craniopharyngioma

General

  • Papillary craniopharyngioma is a solid or partially cystic, non-keratinising squamous epithelial tumour.
  • It typically develops in the infundibulotuberal region of the third ventricle floor and occurs most frequently in adults.
  • The tumour is characterised by BRAF p.V600E mutations.

Definition

  • Essential criteria
    • The tumour must be located in the sellar or suprasellar region.
    • It must be composed of benign, non-keratinising mature squamous epithelium covering fibrovascular cores or a cyst wall.
  • Desirable criteria
    • Demonstrable immunoreactivity for the BRAF p.V600E protein or a detected BRAF p.V600E mutation.
    • Absence of nuclear beta-catenin immunoreactivity and absence of CTNNB1 mutations.

Numbers

  • The papillary type accounts for approximately 10 per cent of all craniopharyngioma cases and 12 to 33 per cent of those diagnosed in adults.
  • It is primarily a disease of adults, with a peak incidence between ages 30 and 59.
  • There is no reported predilection for either sex.

Grading

  • CNS WHO grade 1

Histopathology

Macroscopic

  • These tumours are typically solid or mixed solid and cystic masses.
  • They are generally spherical and have a cauliflower-like configuration.
  • Calcifications are generally absent.
  • The cyst contents are typically described as viscous and yellow.
notion image

Microscopic

  • The tumour consists of well-differentiated mature squamous epithelium that lacks stellate reticulum and wet keratin.
  • Basal cell layer crowding is present, but there is no pronounced palisading.
  • Epithelial and collagenous whorls may be present.
  • Up to one-third of cases contain PAS-positive goblet cells or ciliated epithelium.
A) Papillary architecture B) Well-differentiated non-keratinizing squamous epi thelium covering fibrovascular cores that contain a low density of fibroblasts and immune cells Including lymphocytes, macrophages, and neutrophils C) Well-differentiated non-keratinizing squamous epithelium with intercellular bridges and abundant tumour-infiltrating neutrophils, which are common in these tumours D) Immunohistochemistry tor CK5/6 (an antibody against the intermediate-weight keratins CK5 [58 kDa] and CK6 [56 kDa]) is positive throughout all layers. Staining for CK19 is also positive. Another marker commonly used to assess squamous cell carcinomas of all types, p63, is also immunoreactive in almost all papillary and adamantmomatous craniopharyngiomas
A) Papillary architecture
B) Well-differentiated non-keratinizing squamous epi thelium covering fibrovascular cores that contain a low density of fibroblasts and immune cells Including lymphocytes, macrophages, and neutrophils
C) Well-differentiated non-keratinizing squamous epithelium with intercellular bridges and abundant tumour-infiltrating neutrophils, which are common in these tumours
D) Immunohistochemistry tor CK5/6 (an antibody against the intermediate-weight keratins CK5 [58 kDa] and CK6 [56 kDa]) is positive throughout all layers. Staining for CK19 is also positive. Another marker commonly used to assess squamous cell carcinomas of all types, p63, is also immunoreactive in almost all papillary and adamantmomatous craniopharyngiomas

Immunophenotype

  • Tumour cells express p63, high-molecular-weight cytokeratins such as CK5/6, and low- to intermediate-weight keratins including CK7, CK17, and CK19.
  • PDL1 is expressed in multiple layers of tumour cells circumferentially surrounding the stroma.
  • Nearly all tumours show mutation-specific immunoreactivity for BRAF p.V600E across the epithelium.
  • Beta-catenin expression is confined to the cytoplasmic membrane.

Genetic profile

  • Activation of the MAPK/ERK pathway is driven by BRAF p.V600E mutations.
  • Genomic copy-number profiles are typically stable.

Localisation

  • There is a strong predilection for the infundibulum and tuber cinereum of the third ventricle floor.
  • Tumours can expand into the third ventricle cavity or be located entirely within it.
  • Intrasellar involvement is not common.

Clinical features

  • Headache and visual deficits are the primary manifestations.
  • Preoperative hypothalamic disturbances, such as weight gain and psychiatric issues, occur in 63 per cent of cases.
  • Hydrocephalus is found in 30 per cent of patients.
  • Symptoms may also include alterations in core body temperature and sleep-wake cycles.

Radiological features

  • On MRI, tumours are often solid and spherical rather than lobulated or irregular.
  • Contrast enhancement is usually homogeneous.
  • Cystic lesions often feature a solid cauliflower-like nodule.
  • Calcification is infrequently seen compared to the adamantinomatous type.

Management

  • Surgery resection + radiotherapy
    • Safe total surgical resection is the goal when feasible.
    • Adjuvant radiation or techniques such as proton beam therapy are considered for residual disease.
  • Targeted therapy using BRAF and MEK inhibitors is a therapeutic option currently being evaluated in clinical trials.

Prognosis

  • Overall survival rates are high, reported between 54 and 96 per cent at 5 years in mixed cohorts.
  • Local recurrence occurs in approximately 20 to 35 per cent of patients.
  • Quality of life is a major consideration due to potential hypothalamic damage causing obesity and metabolic syndrome.
  • Malignant transformation is exceedingly rare.